NAEP Technical DocumentationFinal Primary Sampling Unit (PSU) Strata for the 2006 Assessment

The strata were defined using the selected stratifiers from the stepwise regression analysis (see Stepwise Regression Analysis Results for PSU Stratification). The cutoffs were selected so that roughly equal measures of size were represented by each stratum.

Stratification for Northeast metropolitan noncertainty primary sampling units (PSUs), by stratum: 2006
Stratum	Primary stratifier	Secondary stratifier	PSUs	Measure of size
Total	†	†	46	4,709,000
1	Percent child poverty <= 10.1%	Percent Black <= 15.9%	8	586,000
2	Percent child poverty <= 10.1%	15.9% < Percent Black <= 27.7%	2	553,000
3	10.1% < Percent child poverty <= 12.5%	Percent Black <= 14.9%	7	595,000
4	10.1% < Percent child poverty <= 12.5%	14.9% < Percent Black <= 38.2%	4	628,000
5	12.5% < Percent child poverty <= 13.4%	†	5	552,000
6	13.4% < Percent child poverty <= 15.1%	†	7	609,000
7	15.1% < Percent child poverty <= 17%	†	5	554,000
8	17% < Percent child poverty <= 20.7%	†	8	632,000
Mean	†	†	†	589,000
† Not applicable. NOTE: Measures of size are rounded to the nearest thousand. Numbers may not sum to total due to rounding. Black includes African American. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2006.

Stratification for Northeast non-metropolitan noncertainty primary sampling sampling units (PSUs), by stratum: 2006
Stratum	Primary stratifier	PSUs	Measure of size
Total	†	50	1,176,000
1	Percent child poverty <= 15.7%	23	597,000
2	15.7% < Percent child poverty <= 22.8%	27	579,000
Mean	†	†	588,000
† Not applicable. NOTE: Measures of size are rounded to the nearest thousand. Numbers may not sum to total due to rounding. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2006.

Stratification for Midwest metropolitan noncertainty primary sampling units (PSUs), by stratum: 2006
Stratum	Primary stratifier	Secondary stratifier	Tertiary stratifier	PSUs	Measure of size
Total	†	†	†	100	7,407,000
1	Child poverty <= 12.5%	†	Pct Asian <= 1.1%	17	628,000
2	Child poverty <= 12.5%	†	1.1% < Pct Asian <= 1.4%	4	636,000
3	Child poverty <= 12.5%	†	1.4% < Pct Asian <= 2.4%	8	580,000
4	Child poverty <= 12.5%	†	2.4% < Pct Asian <= 2.6%	3	664,000
5	Child poverty <= 12.5%	†	2.6% < Pct Asian <= 3.4%	7	585,000
6	Child poverty <= 12.5%	†	3.4% < Pct Asian <= 10.3%	13	603,000
7	12.5% < Child poverty <= 12.9%	†	†	6	608,000
8	12.9% < Child poverty <= 14.5%	†	Pct Asian <= 1.3%	7	626,000
9	12.9% < Child poverty <= 14.5%	†	1.3% < Pct Asian <= 2.7%	7	622,000
10	14.5% < Child poverty <= 27.6%	Med HH Income <= $38,291	†	17	621,000
11	14.5% < Child poverty <= 27.6%	$38,291 < Med HH Income <= $46,460	Pct Asian <= 0.9%	7	594,000
12	14.5% < Child poverty <= 27.6%	$38,291 < Med HH Income <= $46,460	0.9% < Pct Asian <= 3.1%	4	640,000
Mean	†	†	†	†	617,000
† Not applicable. NOTE: Measures of size are rounded to the nearest thousand. Numbers may not sum to total due to rounding. Med HH Income = Median household income. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2006 Assessment.

Stratification for Midwest non-metropolitan noncertainty primary sampling units (PSUs), by stratum: 2006
Stratum	Primary stratifier	Secondary stratifier	Tertiary stratifier	PSUs	Measure of size
Total	†	†	†	249	3,710,000
1	Percent child poverty <= 15.7%	Percent college grd <= 12.5%	†	41	620,000
2	Percent child poverty <= 15.7%	12.5% < Percent college grd <= 36%	Percent BHI <= 4.2%	42	617,000
3	Percent child poverty <= 15.7%	12.5% < Percent college grd <= 36%	4.2% < Percent BHI <= 8.5%	42	618,000
4	Percent child poverty <= 15.7%	12.5% < Percent college grd <= 36%	8.5% < Percent BHI <= 41.4%	38	620,000
5	15.7% < Percent child poverty <= 45.5%	Percent college grd <= 13.2%	†	41	615,000
6	15.7% < Percent child poverty <= 45.5%	13.2% < Percent college grd <= 23%	†	45	620,000
Mean	†	†	†	†	618,000
† Not applicable. NOTE: Measures of size are rounded to the nearest thousand. Numbers may not sum to total due to rounding. BHI = Black, Hispanic, or American Indian. Black includes African American and Hispanic includes Latino. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2006.

Stratification for South metropolitan noncertainty primary sampling units (PSUs), by stratum: 2006
Stratum	Primary stratifier	Secondary stratifier	Tertiary stratifier	PSUs	Measure of size
Total	†	†	†	153	12,639,000
1	Percent child poverty <= 22.7%	Percent Black <= 39.7%	Percent Hispanic <= 1.7%	16	572,000
2	Percent child poverty <= 22.7%	Percent Black <= 39.7%	1.7% < Percent Hispanic <= 2.6%	12	626,000
3	Percent child poverty <= 22.7%	Percent Black <= 39.7%	2.6% < Percent Hispanic <= 2.7%	3	553,000
4	Percent child poverty <= 22.7%	Percent Black <= 39.7%	2.7% < Percent Hispanic <= 3.0%	8	548,000
5	Percent child poverty <= 22.7%	Percent Black <= 39.7%	3.0% < Percent Hispanic <= 3.5%	7	583,000
6	Percent child poverty <= 22.7%	Percent Black <= 39.7%	3.5% < Percent Hispanic <= 4.2%	6	695,000
7	Percent child poverty <= 22.7%	Percent Black <= 39.7%	4.2% < Percent Hispanic <= 4.8%	4	562,000
8	Percent child poverty <= 22.7%	Percent Black <= 39.7%	4.8% < Percent Hispanic <= 5.5%	6	495,000
9	Percent child poverty <= 22.7%	Percent Black <= 39.7%	5.5% < Percent Hispanic <= 7.3%	8	584,000
10	Percent child poverty <= 22.7%	Percent Black <= 39.7%	7.3% < Percent Hispanic <= 8.5%	5	522,000
11	Percent child poverty <= 22.7%	Percent Black <= 39.7%	8.5% < Percent Hispanic <= 9.1%	4	631,000
12	Percent child poverty <= 22.7%	Percent Black <= 39.7%	9.1% < Percent Hispanic <= 11.2%	6	607,000
13	Percent child poverty <= 22.7%	Percent Black <= 39.7%	11.2% < Percent Hispanic <= 14.6%	8	544,000
14	Percent child poverty <= 22.7%	Percent Black <= 39.7%	14.6% < Percent Hispanic <= 21.1%	6	491,000
15	Percent child poverty <= 22.7%	Percent Black <= 39.7%	21.1% < Percent Hispanic <= 30.8%	6	693,000
16	Percent child poverty <= 22.7%	Percent Black <= 39.7%	30.8% < Percent Hispanic <= 51.2%	6	576,000
17	Percent child poverty <= 22.7%	39.7% < Percent Black <= 56.6%	Percent Hispanic <= 2.7%	6	527,000
18	Percent child poverty <= 22.7%	39.7% < Percent Black <= 56.6%	2.7% < Percent Hispanic <= 7.8%	6	648,000
19	22.7% < Percent child poverty <= 24.3%	†	†	11	479,000
20	24.3% < Percent child poverty <= 45.7%	Percent Black <= 2%	†	4	657,000
21	24.3% < Percent child poverty <= 45.7%	2% < Percent Black <= 60.8%	Percent Hispanic <= 3.8%	11	531,000
22	24.3% < Percent child poverty <= 45.7%	2% < Percent Black <= 60.8%	3.8% < Percent Hispanic <= 64.1%	4	515,000
Mean	†	†	†	†	575,000
† Not applicable. NOTE: Measures of size are rounded to the nearest thousand. Numbers may not sum to total due to rounding. Black includes African American and Hispanic includes Latino. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2006.

Stratification for South non-metropolitan noncertainty primary sampling units (PSUs), by stratum: 2006
Stratum	Primary stratifier	Secondary stratifier	Tertiary stratifier	PSUs	Measure of size
Total	†	†	†	269	5,270,000
1	Percent Black <=31.2%	Median HH income <= $36,049	Percent Asian <= 0.2%	32	525,000
2	Percent Black <=31.2%	Median HH income <= $36,049	0.2% < Percent Asian < 0.3%	29	528,000
3	Percent Black <=31.2%	Median HH income <= $36,049	Percent Asian = 0.3%	32	529,000
4	Percent Black <=31.2%	Median HH income <= $36,049	0.3% < Percent Asian <= 0.4%	29	526,000
5	Percent Black <=31.2%	Median HH income <= $36,049	0.4% < Percent Asian <= 0.7%	26	530,000
6	Percent Black <=31.2%	Median HH income <= $36,049	0.7% < Percent Asian <= 3.0%	26	526,000
7	Percent Black <=31.2%	$36,049 < Median HH income <= $54,721	†	21	529,000
8	31.2% < Percent Black <=51.3%	Median HH income <= $29,555	†	25	529,000
9	31.2% < Percent Black <=51.3%	$29,555 < Median HH income <= $44,421	†	23	527,000
10	51.3% < Percent Black <=79.4%	†	†	26	521,000
Mean	†	†	†	†	527,000
† Not applicable. NOTE: Measures of size are rounded to the nearest thousand. Numbers may not sum to total due to rounding. Black includes African American. Median HH income = median household income. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2006.

Stratification for West metropolitan noncertainty primary sampling units (PSUs), by stratum: 2006
Stratum	Primary stratifier	Secondary stratifier	PSUs	Measure of size
Total	†	†	71	6,440,000
1	Percent high school graduate <= 70%	Percent college graduates <= 13.5%	7	591,000
2	Percent high school graduate <= 70%	13.5% < Percent college graduates <= 22.5%	4	497,000
3	70% < Percent high school graduate <= 78.9%	†	6	500,000
4	78.9% < Percent high school graduate <= 79.6%	†	3	569,000
5	79.6% < Percent high school graduate <= 88.3%	Percent college graduates <= 21.8%	14	548,000
6	79.6% < Percent high school graduate <= 88.3%	21.8% < Percent college graduates <= 25.5%	8	542,000
7	79.6% < Percent high school graduate <= 88.3%	25.5% < Percent college graduates <= 26.9%	4	519,000
8	79.6% < Percent high school graduate <= 88.3%	26.9% < Percent college graduates <= 27.8%	3	541,000
9	79.6% < Percent high school graduate <= 88.3%	27.8% < Percent college graduates <= 30.3%	3	545,000
10	79.6% < Percent high school graduate <= 88.3%	30.3% < Percent college graduates <= 39.5%†	3	520,000
11	88.3% < Percent high school graduate <= 90.1%	†	8	524,000
12	90.1% < Percent high school graduate <= 93.1%	†	8	544,000
Mean	†	†	†	537,000
† Not applicable. NOTE: Measures of size are rounded to the nearest thousand. Numbers may not sum to total due to rounding. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2006.

Stratification for West non-metropolitan noncertainty primary sampling units (PSUs), by stratum: 2006
Stratum	Primary stratifier	Secondary stratifier	Tertiary stratifier	PSUs	Measure of size
Total	†	†	†	102	1,724,000
1	Percent college graduates <=21%	Med child poverty <= 17.3%	†	26	431,000
2	Percent college graduates <=21%	17.3% < Med child poverty <= 43%	Percent HS grads <= 77.3%	23	427,000
3	Percent college graduates <=21%	17.3% < Med child poverty <= 43%	77.3% < Percent HS grads <= 86.4%	28	432,000
4	21% < Percent college graduates <=42.6%	†	†	25	434,000
Mean	†	†	†	†	431,000
† Not applicable. NOTE: Measures of size are rounded to the nearest thousand. Numbers may not sum to total due to rounding. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2006.

Last updated 15 December 2009 (JL)

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